This circuit was found in a 90s Electronic Engineering. The circuit has the tube's critical element. Operational amplifiers support equivalents.
This circuit was designed to power the previous circuits of the wireless sound system, but it can...
This circuit is from the documentation of Radio Shack 1975. It can be mounted with 12 V relays,...
This circuit is suggested by the Optoelectronics Sourcebook by Texas Instruments when AC signals...